VoIP glossary
What is G.729?
G.729 is a compressed voice codec that sends speech at 8 kbit/s, about one third of G.711’s bandwidth on the wire, at the cost of slightly lower quality.
G.729 explained
G.729 is popular on wholesale routes and low-bandwidth links because it fits many more calls into the same pipe. Speech remains clear, but it is less tolerant of packet loss, and it cannot carry fax or modem tones, so fax needs T.38 instead.
Licensing used to be a barrier, but the main patents have expired and most systems now include G.729 by default. When it is used on one leg and G.711 on another, something in between has to transcode, which adds a little delay.
Example
A call centre with 60 agents on a 10 Mbit/s uplink uses G.729, which needs about 1.9 Mbit/s each way for all 60 calls instead of about 5.2 Mbit/s with G.711.
Put it into practice
Prepaid SIP trunks and wholesale routes from $200. Ask sales for rates or the NOC for a technical answer.